The HTTP server in Cisco IOS on Catalyst switches does not properly handle TCP socket events, which allows remote attackers to cause a denial of service (device crash) via crafted packets on TCP port (1) 80 or (2) 443, aka Bug ID CSCuc53853.

Cisco CatOS 5.x before 5.5(20) through 8.x before 8.2(2) and 8.3(2)GLX, as used in Catalyst switches, allows remote attackers to cause a denial of service (system crash and reload) by sending invalid packets instead of the final ACK portion of the three-way handshake to the (1) Telnet, (2) HTTP, or (3) SSH services, aka "TCP-ACK DoS attack."

Unspecified Cisco Catalyst Switches allow remote attackers to cause a denial of service (device crash) via an IP packet with the same source and destination IPs and ports, and with the SYN flag set (aka LanD). NOTE: the provenance of this issue is unknown; the details are obtained solely from the BID.

The SNMP implementation in Cisco IOS 15.1(2)SG4 on Catalyst 4500 devices, when single-switch Virtual Switching System (VSS) is configured, allows remote authenticated users to cause a denial of service (device crash) by performing SNMP polling, aka Bug ID CSCuq04574.